// @strict: true
type Cb<T> = {noAlias: () => T}["noAlias"]; // `"noAlias"` here prevents an alias symbol from being made
// which means the comparison will definitely be structural, rather than by variance

declare const x: Cb<Cb<Cb<Cb<number>>>>; // one more layer of `Cb` adn we'd get a `true` from the deeply-nested symbol check
declare let y: Cb<Cb<Cb<Cb<string>>>>;
y = x;